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1
Heglund, N. C., and C. R. Taylor. "Speed, stride frequency and energy cost per stride: how do they change with body size and gait?" Journal of Experimental Biology 138, no. 1 (September 1, 1988): 301–18. http://dx.doi.org/10.1242/jeb.138.1.301.
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In this study we investigate how speed and stride frequency change with body size. We use this information to define ‘equivalent speeds’ for animals of different size and to explore the factors underlying the six-fold difference in mass-specific energy cost of locomotion between mouse- and horse-sized animals at these speeds. Speeds and stride frequencies within a trot and a gallop were measured on a treadmill in 16 species of wild and domestic quadrupeds, ranging in body size from 30 g mice to 200 kg horses. We found that the minimum, preferred and maximum sustained speeds within a trot and a gallop all change in the same rather dramatic manner with body size, differing by nine-fold between mice and horses (i.e. all three speeds scale with about the 0.2 power of body mass). Although the absolute speeds differ greatly, the maximum sustainable speed was about 2.6-fold greater than the minimum within a trot, and 2.1-fold greater within a gallop. The frequencies used to sustain the equivalent speeds (with the exception of the minimum trotting speed) scale with about the same factor, the −0.15 power of body mass. Combining this speed and frequency data with previously published data on the energetic cost of locomotion, we find that the mass-specific energetic cost of locomotion is almost directly proportional to the stride frequency used to sustain a constant speed at all the equivalent speeds within a trot and a gallop, except for the minimum trotting speed (where it changes by a factor of two over the size range of animals studied). Thus the energy cost per kilogram per stride at five of the six equivalent speeds is about the same for all animals, independent of body size, but increases with speed: 5.0 J kg-1 stride-1 at the preferred trotting speed; 5.3 J kg-1 stride-1 at the trot-gallop transition speed; 7.5 J kg-1 stride-1 at the preferred galloping speed; and 9.4 J kg-1 stride-1 at the maximum sustained galloping speed. The cost of locomotion is determined primarily by the cost of activating muscles and of generating a unit of force for a unit of time. Our data show that both these costs increase directly with the stride frequency used at equivalent speeds by different-sized animals. The increase in cost per stride with muscles (necessitating higher muscle forces for the same ground reaction force) as stride length increases both in the trot and in the gallop.
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Riviere, C., P. Lauret, J. F. Manicom Ramsamy, and Y. Page. "A Bayesian Neural Network approach to estimating the Energy Equivalent Speed." Accident Analysis & Prevention 38, no. 2 (March 2006): 248–59. http://dx.doi.org/10.1016/j.aap.2005.08.008.
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Van Sark, Wilfried G. J. H. M., Henrik C. Van der Velde, Jan P. Coelingh, and Wim A. A. M. Bierbooms. "Do we really need rotor equivalent wind speed?" Wind Energy 22, no. 6 (March 6, 2019): 745–63. http://dx.doi.org/10.1002/we.2319.
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Li, Yang, and Xiaohong Jiao. "Energy management strategy for hybrid electric vehicles based on adaptive equivalent consumption minimization strategy and mode switching with variable thresholds." Science Progress 103, no. 1 (September 27, 2019): 003685041987499. http://dx.doi.org/10.1177/0036850419874992.
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To improve the real-time capability, adaptivity, and efficiency of the energy management strategy in the actual driving cycle, a real-time energy management strategy is investigated for commute hybrid electric vehicles, which integrates mode switching with variable threshold and adaptive equivalent consumption minimization strategy. The proposed strategy includes offline and online parts. In the offline part based on the historical traffic data on the route of the commute vehicle, particle swarm optimization is applied to optimize all the thresholds of mode switching, equivalence factor of the equivalent consumption minimization strategy, and the engine torque and speed at the engine-alone propelling mode so as to establish their mappings on the battery state of charge and power demand. In the online part, the established mappings are involved in the energy management supervisor to generate timely appropriate mode switching signals, and an adaptive equivalence factor for instantaneous optimization equivalent consumption minimization strategy and the optimal engine torque and speed at engine-alone propelling mode. To fully demonstrate the effectiveness of the proposed strategy, the simulation results and comparison with some other strategies and the benchmark dynamic programming strategy are presented by implementing the strategies on the GT-SUITE test platform. The comparison result indicates that the control effect of the proposed energy management strategy is much nearer to that of the benchmark dynamic programming than those of other strategies (the rule-based control, the conventional equivalent consumption minimization strategy, the adaptive equivalent consumption minimization strategy, the rule-based-equivalent consumption minimization strategy, and the stochastic dynamic programming strategy) with the respective improvement in fuel efficiency by 25.9%, 13.25%, 4.6%, 1.32%, and 1.13%.
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Yao, Shuguang, Kaibo Yan, Sisi Lu, and Ping Xu. "Equivalence study involving rail vehicle collision test conditions." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 233, no. 1 (June 3, 2018): 73–89. http://dx.doi.org/10.1177/0954409718779940.
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In the context of rail vehicle collision tests, which incur high costs and consume substantial time and energy, the equivalence between a single vehicle crashing into a rigid wall and two identical vehicles colliding with each other was studied. Taking the car body as a rigid body, a three-dimensional multi-body dynamic model was built to simulate a single-vehicle impact and a collision between two identical vehicles; the results showed that the condition of a single vehicle crashing into a rigid wall at a speed of [Formula: see text] can be used to replace the condition of one vehicle moving at a speed of v and crashing into an identical vehicle that is stationary. However, the actual collision is a strong nonlinear process, and it is necessary to conduct the equivalent test of the condition of collision. Based on the similarity theory, the scaled equivalent vehicle model is established. Through a series of scaled model tests, the following conclusion is drawn: if one vehicle moving at a speed of vcrashes into another identical vehicle that is stationary, one can equivalently use a single vehicle with a speed of [Formula: see text] (units: m/s) that crashes into a rigid wall. This study provides practical support for the equivalence of vehicle collision test conditions and holds great value for engineering applications.
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Yan, Jing Ru, Jin Yao Zhu, Xue Bing Zheng, and Ran Li. "The Equivalent Method of Wind Farms Considering Wake Effect." Advanced Materials Research 860-863 (December 2013): 237–41. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.237.
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It analyses the model of wake effect of wind farm in detail. Considering the energy loss caused by wake effect on the wind speed of wind turbine in different locations, the output of whole wind farm can be evaluated via the model, including the wind speed distribution. Then, it determines a kind of equivalent method of wind farm based on the output characteristic of the port of wind farm.
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Liu, Yongqian, Yanhui Qiao, Shuang Han, Tao Tao, Jie Yan, Li Li, Galsan Bekhbat, and Erdenebat Munkhtuya. "Rotor equivalent wind speed calculation method based on equivalent power considering wind shear and tower shadow." Renewable Energy 172 (July 2021): 882–96. http://dx.doi.org/10.1016/j.renene.2021.03.089.
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RAHVAR, SOHRAB, and YOUSEF SOBOUTI. "AN INVERSE f(R) GRAVITATION FOR COSMIC SPEED UP, AND DARK ENERGY EQUIVALENT." Modern Physics Letters A 23, no. 23 (July 30, 2008): 1929–37. http://dx.doi.org/10.1142/s0217732308026042.
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To explain the cosmic speed up, brought to light by the recent SNIa and CMB observations, we propose the following: (a) In a spacetime endowed with a FRW metric, we choose an empirical scale factor that best explains the observations. (b) We assume a modified gravity, generated by an unspecified field Lagrangian, f(R). (c) We use the adopted empirical scale factor to work back retroactively to obtain f(R), hence the term "Inverse f(R)". (d) Next we consider the classic GR and a conventional FRW universe that, in addition to its known baryonic content, possesses a hypothetical "Dark Energy" component. We compare the two scenarios and find the density, the pressure, and the equation of the state of the Dark Energy required to make up for the differences between the conventional and the modified GR models.
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Maitra, Arijit, and Ken A. Dill. "Bacterial growth laws reflect the evolutionary importance of energy efficiency." Proceedings of the National Academy of Sciences 112, no. 2 (December 29, 2014): 406–11. http://dx.doi.org/10.1073/pnas.1421138111.
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We are interested in the balance of energy and protein synthesis in bacterial growth. How has evolution optimized this balance? We describe an analytical model that leverages extensive literature data on growth laws to infer the underlying fitness landscape and to draw inferences about what evolution has optimized inEscherichia coli. IsE. colioptimized for growth speed, energy efficiency, or some other property? Experimental data show that at its replication speed limit,E. coliproduces about four mass equivalents of nonribosomal proteins for every mass equivalent of ribosomes. This ratio can be explained if the cell’s fitness function is the the energy efficiency of cells under fast growth conditions, indicating a tradeoff between the high energy costs of ribosomes under fast growth and the high energy costs of turning over nonribosomal proteins under slow growth. This model gives insight into some of the complex nonlinear relationships between energy utilization and ribosomal and nonribosomal production as a function of cell growth conditions.
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Macurová, Ľudmila, Pavol Kohút, Marek Čopiak, Ladislav Imrich, and Miroslav Rédl. "Determinig the Energy Equivalent Speed by Using Software Based on the Finite Element Method." Transportation Research Procedia 44 (2020): 219–25. http://dx.doi.org/10.1016/j.trpro.2020.02.050.
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Black, Matthew I., Joseph C. Handsaker, Sam J. Allen, Stephanie E. Forrester, and Jonathan P. Folland. "Is There an Optimal Speed for Economical Running?" International Journal of Sports Physiology and Performance 13, no. 1 (January 1, 2018): 75–81. http://dx.doi.org/10.1123/ijspp.2017-0015.
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The influence of running speed and sex on running economy is unclear and may have been confounded by measurements of oxygen cost that do not account for known differences in substrate metabolism, across a limited range of speeds, and differences in performance standard. Therefore, this study assessed the energy cost of running over a wide range of speeds in high-level and recreational runners to investigate the effect of speed (in absolute and relative terms) and sex (men vs women of equivalent performance standard) on running economy. To determine the energy cost (kcal · kg−1 · km−1) of submaximal running, speed at lactate turn point (sLTP), and maximal rate of oxygen uptake, 92 healthy runners (high-level men, n = 14; high-level women, n = 10; recreational men, n = 35; recreational women, n = 33) completed a discontinuous incremental treadmill test. There were no sex-specific differences in the energy cost of running for the recreational or high-level runners when compared at absolute or relative running speeds (P > .05). The absolute and relative speed–energy cost relationships for the high-level runners demonstrated a curvilinear U shape with a nadir reflecting the most economical speed at 13 km/h or 70% sLTP. The high-level runners were more economical than the recreational runners at all absolute and relative running speeds (P < .05). These findings demonstrate that there is an optimal speed for economical running, there is no sex-specific difference, and high-level endurance runners exhibit better running economy than recreational endurance runners.
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Goit, Jay Prakash, Susumu Shimada, and Tetsuya Kogaki. "Can LiDARs Replace Meteorological Masts in Wind Energy?" Energies 12, no. 19 (September 26, 2019): 3680. http://dx.doi.org/10.3390/en12193680.
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This paper discusses whether profiling LiDARs can replace meteorological tower-based wind speed measurement for wind energy applications without severely compromising accuracy. To this end, the accuracy of LiDAR is evaluated in a moderately complex terrain by comparing long-term wind data measured by a profiling LiDAR against those obtained from tower-mounted cup and sonic anemometers. The LiDAR-measured wind speeds show good agreement with those measured using the sonic anemometer, with the slope of regression line being 1.0 and R 2 > 0.99 . Furthermore, the turbulence intensity obtained from the LiDAR has better agreement with that from the sonic anemometer compared to the cup anemometer which showed the lowest turbulence intensities among the three devices. A comparison of the turbulence intensity obtained from the 90th percentile of the standard deviation distribution shows that the LiDAR-measured turbulence intensities are mostly larger (by 2% or less) than those measured by the sonic anemometer. The gust factors obtained from both devices roughly converged to 1.9, showing that LiDAR is able to measure peak wind speed with acceptable accuracy. The accuracy of the wind speed and power distributions measured using the profiling LiDAR are then evaluated by comparing them against the corresponding distributions obtained from the sonic anemometer. Furthermore, the annual capacity factor—for the NREL 5-MW wind turbine—from the LiDAR-measured wind speed is 2% higher than that obtained from the sonic anemometer-measured wind speed. Numerical simulations are performed using OpenFAST in order to compute fatigue loads for the wind speed and turbulence distributions for the LiDAR and the sonic anemometer measurements. It is found that the 20 years lifetime Damage Equivalent Loads (DELs) computed for the LiDAR wind speed were higher than those for the sonic anemometer wind speeds, by 2%–6% for the blade root bending moments and by 11%–13% for the tower base bending moments. This study shows that even with some shortcomings, profiling LiDARs can measure wind speeds and turbulence intensities with acceptable accuracy. Therefore, they can be used to analyze wind resource and wind power potential of prospective sites, and to evaluate whether those sites are suitable for wind energy development.
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Xia, Kaiwen, Cangli Liu, and Patrick Kanopoulos. "On the Energy of Dynamic Fractures." International Journal of Nonlinear Sciences and Numerical Simulation 13, no. 2 (April 1, 2012): 117–23. http://dx.doi.org/10.1515/ijnsns.2011.119.
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Abstract The validity of the constant propagation fracture energy postulation for dynamic fracture is discussed. As shown from existing direct and indirect experimental results, this assumption may not represent the physical reality. For spontaneous fractures, the fracture energy was shown to increase linearly with the crack length, and for dynamic fractures driven by known amplitude impulsive loading (generated by planar impact), the fracture energy was not a constant either. Despite of its phenomenogical origin, the Broberg's theory developed for self-similar crack growth works well for both spontaneous fractures and dynamic fractures produced by well defined dynamic loading. In this theory, the fracture energy is not a constant. Furthermore, with given far-field loading or equivalent far-field loading, the crack speed is uniquely determined by a strength-like material parameter. This parameter is related to the cohesive strength as proposed by H. J. Gao for hyperelastic materials in the crack-tip process zone. It is proposed in this work that the strength-like parameter (or equivalently the constant fracture speed) is a better material parameter to describe the dynamic fracture propagation process for most dynamic fractures.
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Li, Dan-Yun, Dong-Ming Yang, and Zhen-Tao Liu. "Terminal Voltage Control Scheme of Stand-Alone Wind Energy Conversion System with Battery Energy Storage System." Journal of Advanced Computational Intelligence and Intelligent Informatics 24, no. 7 (December 20, 2020): 882–90. http://dx.doi.org/10.20965/jaciii.2020.p0882.
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The terminal voltage is easily affected by the characteristics of loads and variations in wind speed, loads and system parameters in a stand-alone wind energy conversion system. This paper presents a terminal voltage control scheme that combines the equivalent-input-disturbance (EID) and model predictive control (MPC). The total disturbance is observed and compensated in real time by the EID. A battery energy storage system based on MPC is employed to smooth the fluctuation and imbalance in power caused by the variation in wind speed and loads, thereby solving the problem of terminal voltage flicker and instability. The appropriate terminal voltage can be obtained using the proposed scheme, which is a simple design and offers good prospects for actual applications. The simulation results demonstrate the validity of the proposed scheme.
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Jones, Lynnette M., Debra L. Waters, and Michael Legge. "Walking Speed at Self-Selected Exercise Pace Is Lower but Energy Cost Higher in Older Versus Younger Women." Journal of Physical Activity and Health 6, no. 3 (May 2009): 327–32. http://dx.doi.org/10.1123/jpah.6.3.327.
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Background:Walking is usually undertaken at a speed that coincides with the lowest metabolic cost. Aging however, alters the speed–cost relationship, as preferred walking speeds decrease and energy costs increase. It is unclear to what extent this relationship is affected when older women undertake walking as an exercise modality. The aim of this study was to compare the energetic cost of walking at a self-selected exercise pace for 30 min in older and younger women.Methods:The energetic cost of walking was assessed using the energy equivalent of oxygen consumption measured in 18 young (25 to 49 y) and 20 older (50 to 79 y) women who were asked to walk at their “normal” exercise pace on a motorized treadmill for 30 min.Results:The mass-specific net cost of walking (Cw) was 15% higher and self-selected walking speed was 23% lower in the older women than in the younger group. When speed was held constant, the Cw was 0.30 (J · .kg−1 · m−1) higher in the older women.Conclusions:Preferred exercise pace incurs a higher metabolic cost in older women and needs be taken into consideration when recommending walking as an exercise modality.
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Redfern, Stephanie, Joseph B. Olson, Julie K. Lundquist, and Christopher T. M. Clack. "Incorporation of the Rotor-Equivalent Wind Speed into the Weather Research and Forecasting Model’s Wind Farm Parameterization." Monthly Weather Review 147, no. 3 (March 1, 2019): 1029–46. http://dx.doi.org/10.1175/mwr-d-18-0194.1.
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Abstract Wind power installations have been increasing in recent years. Because wind turbines can influence local wind speeds, temperatures, and surface fluxes, weather forecasting models should consider their effects. Wind farm parameterizations do currently exist for numerical weather prediction models. They generally consider two turbine impacts: elevated drag in the region of the wind turbine rotor disk and increased turbulent kinetic energy production. The wind farm parameterization available in the Weather Research and Forecasting (WRF) Model calculates this drag and TKE as a function of hub-height wind speed. However, recent work has suggested that integrating momentum over the entire rotor disk [via a rotor-equivalent wind speed (REWS)] is more appropriate, especially for cases with high wind shear. In this study, we implement the REWS in the WRF wind farm parameterization and evaluate its impacts in an idealized environment, with varying amounts of wind speed shear and wind directional veer. Specifically, we evaluate three separate cases: neutral stability with low wind shear, high stability with high wind shear, and high stability with nonlinear wind shear. For most situations, use of the REWS with the wind farm parameterization has marginal impacts on model forecasts. However, for scenarios with highly nonlinear wind shear, the REWS can significantly affect results.
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Villante, Carlo. "A Procedure for the Derivation of a Schedule-Based Energy-Equivalent Driving Cycle for Urban Buses." Energies 13, no. 3 (January 21, 2020): 518. http://dx.doi.org/10.3390/en13030518.
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The present paper takes the lead from the long-lasting experience gained by the author on mathematical modeling of vehicle energy performances and on the calibration of those models based on real data acquired on buses in real operation. In particular, the paper focuses on a possible way to define a schedule-based energy-equivalent driving cycle which may have a number of applications (e.g., for buses’ performance prediction, propulsion systems choice and net optimization). Specific attention was given to energy-equivalency of the proposed driving cycles to the foreseeable real mission of the vehicles on their scheduled duty (e.g., mean inertial energy on play during vehicle Start and Stops, mean stops in between the arcs, mean vehicle speed and acceleration, etc.): The objective was in fact that of reproducing the same energy characteristics of the real vehicle mission in a simplified way. To this aim, the main energy characteristics of the expected mission were foreseen through a regressive interpolation of data coming from an extensive analysis of onboard measured data, based on independent variables (mean vehicle cruise speed and slope), which could be efficiently estimated by vehicle schedule. There could be a number of possible uses of the so-defined driving cycles (e.g., for buses’ performance prediction, propulsion systems choice and net optimization): All these applications will benefit from the precision of the cycles in predicting energy characteristics of the real vehicle use and will therefore be much more reliable than in usual practice (which normally makes reference to standardized bus cycles with very limited connection to expected vehicle use).
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Kokkos, Nikolaos, Maria Zoidou, Konstantinos Zachopoulos, Meysam Majidi Nezhad, Davide Astiaso Garcia, and Georgios Sylaios. "Wind Climate and Wind Power Resource Assessment Based on Gridded Scatterometer Data: A Thracian Sea Case Study." Energies 14, no. 12 (June 10, 2021): 3448. http://dx.doi.org/10.3390/en14123448.
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The present analysis utilized the 6-hourly data of wind speed (zonal and meridional) for the period between 2011 and 2019, as retrieved from the Copernicus Marine Environmental Service (CMEMS), covering the Thracian Sea (the northern part of the Aegean Sea). Data were estimated from the global wind fields derived from the Advanced Scatterometer (ASCAT) L2b scatterometer on-board Meteorological Operational (METOP) satellites, and then processed towards the equivalent neutral-stability 10 m winds with a spatial resolution of 0.25° × 0.25°. The analysis involved: (a) descriptive statistics on wind speed and direction data; (b) frequency distributions of daily-mean wind speeds per wind direction sector; (c) total wind energy content assessment per wind speed increment and per sector; (d) total annual wind energy production (in MWh/yr); and (e) wind power density, probability density function, and Weibull wind speed distribution, together with the relevant dimensionless shape and scale parameters. Our results show that the Lemnos Plateau has the highest total wind energy content (4455 kWh/m2/yr). At the same time, the area to the SW of the Dardanelles exhibits the highest wind energy capacity factor (~37.44%), producing 7546 MWh/yr. This indicates that this zone could harvest wind energy through wind turbines, having an efficiency in energy production of 37%. Lower capacity factors of 24–28% were computed at the nearshore Thracian Sea zone, producing between 3000 and 5600 MWh/yr.
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Wolf, B. O., K. M. Wooden, and G. E. Walsberg. "Effects of complex radiative and convective environments on the thermal biology of the white-crowned sparrow (Zonotrichia leucophrys gambelii)." Journal of Experimental Biology 203, no. 4 (February 15, 2000): 803–11. http://dx.doi.org/10.1242/jeb.203.4.803.
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The energy budgets of small endotherms are profoundly affected by characteristics of the physical environment such as wind speed, air temperature and solar radiation. Among these, solar radiation represents a potentially very large heat load to small animals and may have an important influence on their thermoregulatory metabolism and heat balance. In this investigation, we examined the interactive effects of wind speed and irradiance on body temperature, thermoregulatory metabolism and heat balance in the white-crowned sparrow (Zonotrichia leucophrys gambelii). We measured changes in metabolic heat production by exposing birds to different wind speeds (0.25, 0.5, 1.0 and 2.0 m s(−1)) and irradiance combinations (<3 W m(−2) and 936+/−11 W m(−2); mean +/− s.d.) at an air temperature of 10 degrees C. Body temperature was not affected by wind speed, but was significantly higher in animals not exposed to simulated solar radiation compared with those exposed at most wind speeds. In the absence of solar radiation, metabolic heat production was strongly affected by wind speed and increased by 30 % from 122 to 159 W m(−2) as wind speed increased from 0.25 to 2.0 m s(−1). Metabolic heat production was even more strongly influenced by wind speed in the presence of simulated solar radiation and increased by 51% from 94 to 142 W m(−2) as wind speed increased from 0.25 to 2. 0 m s(−1). Solar heat gain was negatively correlated with wind speed and declined from 28 to 12 W m(−2) as wind speed increased from 0.25 to 2.0 m s(−1) and, at its maximum, equaled 11% of the radiation intercepted by the animal. The overall thermal impact of the various wind speed and irradiance combinations on the animal's heat balance was examined for each treatment. Under cold conditions, with no solar radiation present, an increase in wind speed from 0.25 to 2.0 m s(−1) was equivalent to a decrease in chamber air temperature of 12.7 degrees C. With simulated solar radiation present, a similar increase in wind speed was equivalent to a decrease in chamber air temperature of 16 degrees C. Overall, shifting environmental conditions from a wind speed of 0.25 m s(−1) and irradiance of 936 W m(−2) to a wind speed of 2.0 m s(−1) with no short-wave radiation present was equivalent to decreasing chamber air temperature by approximately 20 degrees C. The sensitivity to changes in the convective environment, combined with the complex effects of changes in irradiance levels revealed by re-analyzing data published previously, significantly complicates the task of estimating the heat balance of animals in nature.
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Tian, Xin Shou, Zhong Xu Han, and Jian Feng Tian. "A Novel Power Reserve Operating Scheme of DFIG." Applied Mechanics and Materials 427-429 (September 2013): 644–47. http://dx.doi.org/10.4028/www.scientific.net/amm.427-429.644.
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The system equivalent rotary inertia and frequency control capability are decreased with growing continuously of wind power penetration, because the doubly fed induction generator (DFIG) is decoupled from system frequency, which will bring a new challenge to the large wind power integration. On the basic of analyzing power-speed characteristic of DFIG which operates at different wind speeds, the de-load operating strategy of DFIG based on coordinated controlling of over-speed and changing pitch was proposed, at the same time the de-load operating curve of DFIG was given through calculating, and the enhancing of kinetic energy was proved by theoretical analysis. And the power reserve capacity of system is enhanced.
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Gavrilyk, A., and M. Lemishko. "ANALYSIS OF EQUIVALENT FUEL SAVINGS OF ELECTRIC VEHICLES." Bulletin of Lviv State University of Life Safety 20 (January 23, 2020): 85–89. http://dx.doi.org/10.32447/20784643.20.2019.12.
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The development of electric vehicles in the near future is outlined, their general classification and problems of their use are given. The most common energy elements used to power electric traction electric motors are analyzed, their advantages and disadvantages are described. The analysis shows the most economical electric cars in 2018 and describes their traction and speed characteristics. The peculiarities of methodology for determining fuel economy for hybrid vehicles (PHEV - plugin hybrid electric vehicle) and for vehicles running on alternative fuel type (NGV-natural gas vehicle; FCV-fuel cell vehicle) are revealed and the possibility of its improvement is revealed. Methodological bases of estimation of fuel economy of electric vehicles are developed. This will allow potential buyers, owners or economists of the trucking companies to objectively estimate the equivalent fuel consumption and successfully choose one or the other brand of electric vehicle. An algorithm for determining the equivalent fuel economy of electric vehicles was developed and described taking into account the energy price policy for different countries of the world.It is concluded that lithiumion batteries have become the most widespread, as the feeding elements of electric vehicles. It is found that the equivalent fuel consumption is the most objective and informative, from the user's point of view, characterizing the use of electric vehicles compared to indicating the amount of energy (kWh) required to overcome 100 miles of travel. Using the proposed method, the equivalent fuel economy of these electric vehicles is calculated, the results are plotted against. It is established that for Ukraine, considering the cost of energy carriers, the use of electric vehicles is the most costeffective compared to other countries.
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Liu, Jian Ye, Yun Shan Li, Xiao Gu, and Chun Miao Li. "Equivalent Model and Maximum Wind Power Tracking Control Mechanism of Grid-Connected PMSWG." Applied Mechanics and Materials 303-306 (February 2013): 1171–74. http://dx.doi.org/10.4028/www.scientific.net/amm.303-306.1171.
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Based on the speed control system of grid connected direct-drive wind permanent magnet synchronous generators, it is proposed and built up that boost chopper generating equivalent as the model of DC generator. Analyzing the dynamic process of the boost chopper generating equivalent as DC generator, it reveals the relationships between intrinsic variables and puts forward that increasing boost chopper control duty ratio D, namely, increasing the energy storage time of inductance L, and reducing released energy time relatively, it will increase the armature current of the generator, otherwise, it will reduce the current in the current continuous situation. At the same time, according to the principle of maximal wind energy tracking, the paper reveals the control mechanism of maximum wind power tracking of the wind generators. A theoretical basis is provided for the realization of the control of the wind power maximum wind energy tracking.
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Arvidsson, Daniel, Jonatan Fridolfsson, Christoph Buck, Örjan Ekblom, Elin Ekblom-Bak, Lauren Lissner, Monica Hunsberger, and Mats Börjesson. "Reexamination of Accelerometer Calibration with Energy Expenditure as Criterion: VO2net Instead of MET for Age-Equivalent Physical Activity Intensity." Sensors 19, no. 15 (August 1, 2019): 3377. http://dx.doi.org/10.3390/s19153377.
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Accelerometer calibration for physical activity (PA) intensity is commonly performed using Metabolic Equivalent of Task (MET) as criterion. However, MET is not an age-equivalent measure of PA intensity, which limits the use of MET-calibrated accelerometers for age-related PA investigations. We investigated calibration using VO2net (VO2gross − VO2stand; mL⋅min−1⋅kg−1) as criterion compared to MET (VO2gross/VO2rest) and the effect on assessment of free-living PA in children, adolescents and adults. Oxygen consumption and hip/thigh accelerometer data were collected during rest, stand and treadmill walk and run. Equivalent speed (Speedeq) was used as indicator of the absolute speed (Speedabs) performed with the same effort in individuals of different body size/age. The results showed that VO2net was higher in younger age-groups for Speedabs, but was similar in the three age-groups for Speedeq. MET was lower in younger age-groups for both Speedabs and Speedeq. The same VO2net-values respective MET-values were applied to all age-groups to develop accelerometer PA intensity cut-points. Free-living moderate-and-vigorous PA was 216, 115, 74 and 71 min/d in children, adolescents, younger and older adults with VO2net-calibration, but 140, 83, 74 and 41 min/d with MET-calibration, respectively. In conclusion, VO2net calibration of accelerometers may provide age-equivalent measures of PA intensity/effort for more accurate age-related investigations of PA in epidemiological research.
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Herbst, Lynette, and Jörg Lalk. "A case study of climate variability effects on wind resources in South Africa." Journal of Energy in Southern Africa 25, no. 3 (September 23, 2014): 2–10. http://dx.doi.org/10.17159/2413-3051/2014/v25i3a2652.
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The wind energy sector is one of the most prominent sectors of the renewable energy industry. However, its dependence on meteorological factors subjects it to climate change. Studies analysing the impact of climate change on wind resources usually only model changes in wind speed. Two elements that have to be calculated in addition to wind speed changes are Annual Energy Production (AEP) and Power Density (PD). This is not only because of the inherent variability between wind speed and wind power generated, but also because of the relative magnitudes of change in energy potentially generated at different areas under varied wind climates. In this study, it was assumed that two separate locations would experience a 10% wind speed increase after McInnes et al. (2010). Given the two locations’ different wind speed distributions, a wind speed increase equal in magnitude is not equivalent to similar magnitudes of change in potential energy production in these areas. This paper demonstrates this fact for each of the case studies. It is of general interest to the energy field and is of value since very little literature exists in the Southern African context on climate change- or variability-effects on the (wind) energy sector. Energy output is therefore dependent not only on wind speed, but also wind turbine characteristics. The importance of including wind power curves and wind turbine generator capacity in wind resource analysis is emphasised.
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Yoon, Ranhee, Birhan Abebaw Negash, Wonhee You, Jungyoul Lim, Jinho Lee, Changyoung Lee, and Kwansup Lee. "Capsule Vehicle Dynamics Based on Levitation Coil Design Using Equivalent Model of a Sidewall Electrodynamic Suspension System." Energies 14, no. 16 (August 13, 2021): 4979. http://dx.doi.org/10.3390/en14164979.
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A levitation system based on sidewall electrodynamic suspension (EDS) is considered for a capsule vehicle, which is a next-generation high-speed transportation system currently being studied. This levitation system does not require controlling of the gap between the guideway and the vehicle on which the superconducting electromagnet is mounted. However, when the vehicle is operated in a levitated state, the ride comfort is worse than that of the levitation system based on electromagnetic suspension (EMS), making it necessary to develop methods that can ensure good riding comfort. In addition, because the EDS system is complex and nonlinear with a combination of electromagnetics and mechanical dynamics, it is complicated to analyze the dynamic characteristics of the capsule vehicle, and the corresponding numerical analysis is time-consuming. Therefore, to easily understand the running dynamics of a capsule vehicle in the sidewall EMS system, the magnetic suspension characteristics corresponding to the primary suspension are simply modeled by considering the levitation stiffness in the vertical direction and the guidance stiffness in the lateral direction, similar to that in the case of the mechanical suspension. In this study, mathematical models of the levitation and guidance stiffnesses with respect to the speed and position of a vehicle body running at high speeds in a levitated state in the sidewall EDS system were derived for three design proposals of the levitation coil. The dynamic behavior of the vehicle based on the three design proposals was investigated by simulating a capsule vehicle model with 15 degrees of freedom.
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Xu, Jianzhong, Yuchen Zhao, Chengyong Zhao, and Hui Ding. "Unified High-Speed EMT Equivalent and Implementation Method of MMCs With Single-Port Submodules." IEEE Transactions on Power Delivery 34, no. 1 (February 2019): 42–52. http://dx.doi.org/10.1109/tpwrd.2018.2875073.
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Chin, Takaaki, Katsuhiro Machida, Seishi Sawamura, Ryouichi Shiba, Hiroko Oyabu, Yuji Nagakura, Izumi Takase, and Akio Nakagawa. "Comparison of Different Microprocessor Controlled Knee Joints on the Energy Consumption during Walking in Trans-Femoral Amputees: Intelligent Knee Prosthesis (IP) Versus C-Leg." Prosthetics and Orthotics International 30, no. 1 (April 2006): 73–80. http://dx.doi.org/10.1080/03093640500533414.
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The purpose of this study was to investigate the characteristic differences between the IP and C-Leg by making a comparative study of energy consumption and walking speeds in trans-femoral amputees. The subjects consisted of four persons with traumatic trans-femoral amputations aged 17 – 33 years who had been using the IP and were active in society. Fourteen able-bodied persons served as controls. First the energy consumption at walking speeds of 30, 50, 70, and 90 m/min was measured when using the IP. Then the knee joint was switched to the C-Leg. The same energy consumption measurement was taken once the subjects were accustomed to using the C-Leg. The most metabolically efficient walking speed was also determined. At a walking speed of 30 m/min using the IP and C-Leg, the oxygen rate (ml/kg/min) was, on average, 42.5% and 33.3% higher ( P<0.05) than for the able-bodied group. At 50 m/min, the equivalent figures were 56.6% and 49.5% ( P<0.05), while at 70 m/min the figures were 57.8% and 51.2% ( P<0.05), and at 90 m/min the figures were 61.9% and 55.2% ( P<0.05%). Comparing the oxygen rates for the subjects using the IP and C-Leg at walking speeds of 30 m/min and 90 m/min it was found that subjects who used C-Leg walked somewhat more efficiently than those who used IP. However, there was no significant difference between the two types at each walking speed. It was also determined that the most energy-efficient walking speed for subjects using the IP and C-Leg was the same as for the controls. Although the subjects in this study walked with comparable speed and efficiency whether they used the IP or C-Leg, the subjects' energy consumption while walking with the IP and C-Leg at normal speeds were much lower than previously reported. This study suggested that the microprocessor controlled knee joints appeared to be valid alternative for improving walking performance of trans-femoral amputees.
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Khramshina, Ekaterina A., Alexander S. Karandaev, and Rifkhat R. Khramshin. "Improving Energy Efficiency of the Variable Frequency Drive of the Forced-Draught Fan with the Two-Speed Asynchronous Motor." Applied Mechanics and Materials 792 (September 2015): 128–33. http://dx.doi.org/10.4028/www.scientific.net/amm.792.128.
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Based on the example of forced-draught fans of the GOFHWB-100 series hot water boilers (gas and oil fired hot water boilers) power supply reserves of the electric drive with two-speed asynchronous motor have been determined. The structural chart of the developed control system of the electric drive with winding changeover depending on the boiler performance is provided. The paper considers power consumption of electric drive in the variable frequency speed control mode at the motor operation on the high and low speed windings. It presents methods for calculation of energy performance based on computing the equivalent efficiency of the fluid-handling application. The analysis of the efficiency change has proved that the variable frequency control enables electric power savings at the low speed winding by 5 to 6%. The results obtained are recommended to be widely applied at the change-over of the electric drives with two-speed asynchronous motors to the variable frequency control of performance.
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Amalia, Hindun, Sutikno, Indra Sidharta, Wahyu Wijanarko, and Putu Suwarta. "The Effect of Hollow Glass Reinforced Epoxy in Absorbing Impact Energy for Vehicle Bumper Application." Applied Mechanics and Materials 758 (April 2015): 101–6. http://dx.doi.org/10.4028/www.scientific.net/amm.758.101.
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Safety is one of important factors which has to be considered in designing automobile in the automotive industry. One of the components related to the automobile safety is bumper. Bumpers are attached on front and rear of vehicle’s body in order to protect the body from damage due to low speed crash. In this research, hollow glass microsphere (HGM) reinforced epoxy is used as the material for the bumper since this material has not been applied to this application yet. This research is conducted in order to find the ability of this composite material in absorbing impact energy from low speed crash by using finite element method. Thickness of the bumper varied from 4 mm to 8 mm with 1 mm increment. Low speed collision is simulated by following Economic Commission for Europe Regulation 42. The bumper energy absorption is analyzed and indicated by the internal energy, deformation, and equivalent stress from each bumper’s thickness.
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Hu, Zeyao, Dongli Song, Yuanchen Zeng, and Weihua Zhang. "Analysis of the service life of railway hydraulic dampers considering temperature and loading." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 235, no. 1 (January 6, 2020): 3–11. http://dx.doi.org/10.1177/0954409719898079.
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Hydraulic dampers are mainly used to maintain high-speed trains in a stable state when running at high speed. In this paper, an equivalent method for the lifetime of dampers is proposed to establish the relationship between the long-term loading test and the mileage in service condition. The performance degradation of the damper at different temperatures is calculated using the long-term loading test carried out under the corresponding temperature conditions. Arrhenius model is applied to convert the degradation under different temperatures, and the sensitive parameter is selected for the conversion of the damper’s performance degradation under different temperatures. An energy method is proposed to solve the problem of the damper lifetime under different loads, so as to achieve the equivalent of the damper between the long-term load test and the mileage in service condition. Finally, taking the anti-yaw damper of a certain type of high-speed train in China as the research object, the lifetime equivalent method proposed in this paper is applied and the result showed that the anti-yaw damper had remaining service life after 2.4 million kilometers of service.
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Romaniuk, F. A., Yu V. Rumiantsev, V. Yu Rumiantsev, and I. V. Novash. "Improvement of Algorithm for Formation of Orthogonal Components of Input Quantities in Microprocessor Protection." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 64, no. 2 (April 9, 2021): 95–108. http://dx.doi.org/10.21122/1029-7448-2021-64-2-95-108.
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The use of orthogonal components (OC) underlies the construction of measuring elements of modern protection and automation devices. In most microprocessor-based protections, the orthogonal component of the input signal is extracted using a discrete Fourier transform (DFT). The DFT disadvantages are its low speed, which is more than one period of the fundamental frequency, as well as the sensitivity to the free aperiodic component, which creates significant conversion errors depending on the time constant of its decay. Such a settling time of the true output signal is often unacceptable for the design of high-speed measuring devices. The paper proposes to form the OC of the equivalent signal according to the values of the cosine and sine OC of the fundamental harmonic, formed using the DFT by multiplying them by the resulting correction factor. The developed algorithm for the formation of orthogonal components of input signals in microprocessor protections is characterized by high speed in transient modes and it has wide functionality. So, the proposed digital device for forming the orthogonal components of an equivalent signal, in comparison with digital filter based on the DFT, has an increased operating speed both in the mode of occurrence of a short circuit and during the decay of the monitored signal, while maintaining the same characteristics as in the DFT in other modes. A block diagram of the proposed digital device for forming the OC of an equivalent signal has been developed, all blocks of which can be implemented on a microelectronic and microprocessor element base. A digital model of the specified device has been developed in the dynamic modeling system MatLab-Simulink in accordance with the structural diagram. As a result of the calculations, a significant (up to two times) increase in the performance of the proposed digital device for forming the OC in transient modes has been established in comparison with the shapers based on the DFT.
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Wei, Changyin, Yong Chen, Xiuxiu Sun, and Yue Zhang. "Optimal Equivalent Consumption Minimization Strategy for Plug-In Hybrid Electric Vehicle with Improved Genetic Algorithm." SAE International Journal of Electrified Vehicles 9, no. 2 (December 31, 2020): 143–54. http://dx.doi.org/10.4271/14-09-02-0009.
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The equivalent consumption minimization strategy (ECMS) is a promising energy management approach to low-fuel economy with the outstanding features of high efficiency. In this article, an optimal ECMS by Improved Genetic Algorithm (IGA) is proposed. To this end, we improved the genetic algorithm (GA) from the coding method, initialization mode, and cross and mutation process. And based on the comprehensive energy consumption and Pontryagin’s minimum principle, the equivalent factor was derived. The IGA was used to optimize the equivalent factor. To evaluate the performance of the proposed energy management strategy (EMS), the average efficiency of the engine and the motor was analyzed in an urban area, high-speed area, and the whole area. The comprehensive fuel consumption was used as the energy consumption index, and the battery capacity loss under the transient conditions was amplified to 10 years as the evaluation battery life index. The simulation results show that under the New European Driving Cycle (NEDC), the proposed strategy improves the fuel economy and battery life index by 14.64% and 36.76%, respectively, compared with the rule-based EMS.
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Krishna. S, Mohan, and Febin Daya. J.L. "Effect of Parametric Variations and Voltage Unbalance on Adaptive Speed Estimation Schemes for Speed Sensorless Induction Motor Drives." International Journal of Power Electronics and Drive Systems (IJPEDS) 6, no. 1 (March 1, 2015): 77. http://dx.doi.org/10.11591/ijpeds.v6.i1.pp77-85.
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Speed Estimation without speed sensors is a complex phenomenon and is overly dependent on the machine parameters. It is all the more significant during low speed or near zero speed operation. There are several approaches to speed estimation of an induction motor. Eventually, they can be classified into two types, namely, estimation based on the machine model and estimation based on magnetic saliency and air gap space harmonics. This paper analyses the effect of incorrect setting of parameters like the stator resistance, rotor time constant, load torque variations and also Voltage unbalance on various adaptive control based speed estimation techniques fed from the machine model. It also shows how the convergence mechanisms of the adaptation schemes are affected during these conditions. The equivalent models are built and simulated offline using MATLAB/SIMULINK blocksets and the results are analysed.
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Yang, Z. Q., and Tadashi Fukao. "Equivalent circuit and output characteristics of superhigh-speed reluctance generator taking iron losses into consideration." Electrical Engineering in Japan 110, no. 6 (1990): 80–89. http://dx.doi.org/10.1002/eej.4391100608.
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Datt, Prem, P. K. Srivastava, G. K. Sood, and P. K. Satyawali. "Estimation of equivalent permeability of snowpack using a snowmelt lysimeter at Patsio, northwest Himalaya." Annals of Glaciology 51, no. 54 (2010): 195–99. http://dx.doi.org/10.3189/172756410791386670.
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AbstractThe meltwater percolation process through the snowpack greatly influences its physical and mechanical properties. The percolation process is important for understanding the spring avalanche phenomenon as well as the meltwater runoff for basin hydrology studies. The permeability of individual snow layers depends on parameters such as porosity, pore connectivity and the geometrical shape of the pores. Snowpack equivalent permeability plays an important role in governing the transmission of meltwater through the different layers of the snowpack. In this paper, we present the design, fabrication and installation of a snowmelt lysimeter at Patsio field research station, Himachal Pradesh, India, and determine the snowpack equivalent permeability using lysimeter discharge data. The snowmelt lysimeter, having a collector area of 6.25 m2and a high-capacity snowmelt measuring tipping bucket, was installed on flat ground near the observatory with a data acquisition system. Snowmelt discharge measurements were made for two melt seasons, 2006/07 and 2007/08. Snow and meteorological data were collected at 15 min intervals using a semi-automatic weather station. The hourly surface snowmelt was estimated using an energy-balance approach. The maximum daily discharge was >2 mm w.e.h−1for most of the observation period. The daily mean wave speed of the meltwater front varied from 109 to 285 mm h−1for a daily mean discharge range of 0.6–1.8 mm w.e.h−1, while wave speeds for a particular melt flux of 2 mm w.e.h−1varied between 113 and 486 mm h−1. The pore-size distribution index was estimated using the power-fit relation between wave speed and discharge. The equivalent permeability of the snowpack was found to vary between 3.4 × 10−8and 9.9 × 10−12m2.
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Srivastava, Sachin, U. J. Shenoy, Abhinna Chandra Biswal, and Ganesan Sethuraman. "Impedance seen by Distance Relays on Lines Fed from Fixed Speed Wind Turbines." International Journal of Emerging Electric Power Systems 14, no. 1 (May 30, 2013): 17–24. http://dx.doi.org/10.1515/ijeeps-2013-0026.
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Abstract This paper deals with line protection challenges experienced in a system having substantial wind generation penetration. Two types of generators, thermal synchronous generators and fixed speed wind turbines based on squirrel-cage induction generators, are simulated as thevenin equivalent model, connected to grid with single-circuit transmission line. The paper gives comparative discussion and summarizes analytical investigations carried out on the impedance seen by distance relays by varying fault resistances and grid short circuit MVA, for the protection of such transmission lines during faults.
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Bennewitz, John W., Blaine R. Bigler, Mathias C. Ross, Stephen A. Danczyk, William A. Hargus, and Richard D. Smith. "Performance of a Rotating Detonation Rocket Engine with Various Convergent Nozzles and Chamber Lengths." Energies 14, no. 8 (April 7, 2021): 2037. http://dx.doi.org/10.3390/en14082037.
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A rotating detonation rocket engine (RDRE) with various convergent nozzles and chamber lengths is investigated. Three hundred hot-fire tests are performed using methane and oxygen ranging from equivalence ratio equaling 0.5–2.5 and total propellant flow up to 0.680 kg/s. For the full-length (76.2 mm) chamber study, three nozzles at contraction ratios ϵc = 1.23, 1.62 and 2.40 are tested. Detonation is exhibited for each geometry at equivalent conditions, with only fuel-rich operability slightly increased for the ϵc = 1.62 and 2.40 nozzles. Despite this, counter-propagation, i.e., opposing wave sets, becomes prevalent with increasing constriction. This is accompanied by higher number of waves, lower wave speed Uwv and higher unsteadiness. Therefore, the most constricted nozzle always has the lowest Uwv. In contrast, engine performance increases with constriction, where thrust and specific impulse linearly increase with ϵc for equivalent conditions, with a 27% maximum increase. Additionally, two half-length (38.1 mm) chambers are studied including a straight chamber and ϵc = 2.40 nozzle; these shortened geometries show equal performance to their longer equivalent. Furthermore, the existence of counter-propagation is minimized. Accompanying high-fidelity simulations and injection recovery analyses describe underlying injection physics driving chamber wave dynamics, suggesting the physical throat/injector interaction influences counter-propagation.
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Radhi, Ahmed Thamer, and Wael Hussein Zayer. "Faults diagnosis in stator windings of high speed solid rotor induction motors using fuzzy neural network." International Journal of Power Electronics and Drive Systems (IJPEDS) 12, no. 1 (March 1, 2021): 597. http://dx.doi.org/10.11591/ijpeds.v12.i1.pp597-611.
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The paper deals with faults diagnosis method proposed to detect the inter-turn and turn to earth short circuit in stator winding of three-phase high-speed solid rotor induction motors. This method based on negative sequence current of motor and fuzzy neural network algorithm. On the basis of analysis of 2-D electromagnet field in the solid rotor the rotor impedance has been derived to develop the solid rotor induction motor equivalent circuit. The motor equivalent circuit is simulated by MATLAB software to study and record the data for training and testing the proposed diagnosis method. The numerical results of proposed approach are evaluated using simulation of a three-phase high-speed solid-rotor induction motor of two-pole, 140 Hz. The results of simulation shows that the proposed diagnosis method is fast and efficient for detecting inter-turn and turn to earth faults in stator winding of high-speed solid-rotor induction motors with different faults conditions
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Ge, Y. T., and S. A. Tassou. "Mathematical modelling of supermarket refrigeration systems for design, energy prediction and control." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 214, no. 2 (March 1, 2000): 101–14. http://dx.doi.org/10.1243/0957650001538218.
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This paper describes a mathematical model developed to simulate the performance of supermarket refrigeration systems. Such a model can be used for the comparison of different systems and control strategies in terms of their energy and total equivalent warming impact. The model is based on a large number of component models which have been linked together within the TRNSYS environment. Major component models include the compressor, air-cooled condenser, thermostatic expansion valve, display cabinet and control. The overall system model has been validated against monitored data obtained from both a laboratory-based system and a full-scale system in a supermarket in Scotland. The value of the model is illustrated by determining and comparing the effectiveness of head pressure and variable-speed control against fixed head pressure and constant speed control. It is shown that even at summer ambient conditions the system can be operated without problems at much lower head pressures than is done in practice under fixed-pressure control strategies. The use of variable-speed control on one of the compressors can also provide better control of the suction pressure and a substantial (up to 23 per cent) energy savings compared to on-off control.
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Weyand, Peter G., Bethany R. Smith, Nicole S. Schultz, Lindsay W. Ludlow, Maurice R. Puyau, and Nancy F. Butte. "Predicting metabolic rate across walking speed: one fit for all body sizes?" Journal of Applied Physiology 115, no. 9 (November 1, 2013): 1332–42. http://dx.doi.org/10.1152/japplphysiol.01333.2012.
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We formulated a “one-size-fits-all” model that predicts the energy requirements of level human walking from height, weight, and walking speed. Our three-component model theorizes that the energy expended per kilogram per stride is independent of stature at mechanically equivalent walking speeds. We measured steady-state rates of oxygen uptake of 78 subjects who spanned a nearly twofold range of statures (1.07–2.11 m) and sevenfold range of body masses (16–112 kg) at treadmill speeds from 0.4 to 1.9 m/s. We tested the size independence of the model by deriving best-fit equations in the form of the model on four stature groups ( n ≥ 15): short, moderately short, moderately tall, and tall. The mean walking metabolic rates predicted by these four independently derived equations for the same set of reference subjects ( n = 16; stature range: 1.30–1.90 m) agreed with one another to within an average of 5.2 ± 3.7% at the four intermediate speeds in our protocol. We next evaluated the model's gross predictive accuracy by dividing our 78 subjects into 39 stature-matched pairs of experimental and validation group subjects. The model best-fit equation derived on the experimental group subjects predicted the walking metabolic rates of the validation group subjects to within an average of 8.1 ± 6.7% ( R2 = 0.90; standard error of estimate = 1.34 ml O2·kg−1·min−1). The predictive error of the American College of Sports Medicine equation (18.0 ± 13.1%), which does not include stature as a predictor, was more than twice as large for the same subject group. We conclude that the energy cost of level human walking can be accurately predicted from height, weight, and walking speed.
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Bao, Wei Cheng, Hong Chen, and Yan Mei Liang. "Vibration Analysis on Convey Paper Belt of Infeed Unit." Applied Mechanics and Materials 262 (December 2012): 377–81. http://dx.doi.org/10.4028/www.scientific.net/amm.262.377.
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The precondition of improve the printing press velocity is to maintain the minimum vibration of infeed unit within the range of press speed. Taking advantage of the equivalent relation between the formula of infinitesimal energy and the classic beam theory, the vibration of convey paper belt can be converted into the problem of the beam be stretched and be compressed, and then we utilize the finite element simulation technology to conduct model analysis for the convey paper belt. When the numerical of the belt speed gain ,both the vibration and shape distortion reach the maximum, as well as speed of the infeed unit will be influenced most.
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Sokolovskij, Edgar. "INVESTIGATION OF THE INTERACTION OF AN AUTOMOBILE WHEEL WITH A VERTICAL OBSTACLE." TRANSPORT 20, no. 4 (August 30, 2005): 141–45. http://dx.doi.org/10.3846/16484142.2005.9638011.
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Collision of automobile wheels with a vertical obstacle as a result of which the wheel tire gets dismantled is considered in the present article. The required force and the minimal speed of driving which is equivalent to the expenditures of the kinetic energy necessary for dismantling of the tire from the wheel rim after the collision with an obstacle are ascertained. The values of this force and speed typical of automobiles attributed to different classes, their dependence upon the height of the obstacle and the angle of collision with the obstacle are fixed. A more precise method for the calculation of the automobile speed prior to the traffic accident taking into consideration the expenditures of the kinetic energy necessary for dismantling of the wheel after the occurrence of its collision with a vertical obstacle is suggested.
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Li, Yibo, Heyun Lin, Hai Huang, Hui Yang, Qiancheng Tao, and Shuhua Fang. "Analytical Analysis of a Novel Brushless Hybrid Excited Adjustable Speed Eddy Current Coupling." Energies 12, no. 2 (January 19, 2019): 308. http://dx.doi.org/10.3390/en12020308.
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A novel brushless hybrid excited adjustable speed eddy current coupling is proposed for saving energy in the drive systems of pumps and fans. The topology and operation principle of the coupling are presented. Based on the real flux paths, the fluxes excited by permanent magnet (PM) and field current are analyzed separately. A magnetic circuit equivalent (MEC) model is established to efficiently compute the no-load magnetic field of the coupling. The eddy current and torque are calculated based on the proposed MEC model, Faraday’s law, and Ampere’s law. The resultant magnetic fields, eddy currents, and torques versus slip speeds under different field currents are studied by the MEC-based analytical method and verified by finite element analysis (FEA). The copper loss, core loss, and efficiency were investigated by FEA. The analytically predicted results agree well with the FEA, and the analysis results illustrate that a good speed regulation performance can be achieved by the proposed hybrid excited control.
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Wang, Hongjian, Linlin Wang, and Lixin Pan. "Research on Roll Stabilizing Based on Energy Optimization for Autonomous Surface Vehicle." Journal of Applied Mathematics 2014 (2014): 1–15. http://dx.doi.org/10.1155/2014/347589.
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Considering the case of ASV (autonomous surface vehicle) navigating with low speed near water surface, a new method for design of roll motion controller is proposed in order to restrain wave disturbance effectively and improve roll stabilizing performance. Control system design is based on GPC (general predictive control) theory and working principle of zero-speed fin stabilizer. Coupling horizontal motion model of ASV is decoupled, and an equivalent transfer function of roll motion is obtained and transformed into a discrete difference equation through inverse Laplace transformation and Euler approximation. Finally, predictive model of GPC, namely, the difference equation of roll motion, is given. GPC algorithm of ASV roll motion is derived from performance index based on roll stabilizing performance and energy consumption used for driving fin stabilizer. In allusion to time-variant parameters in roll motion model, recursive least square method is adopted for parameter estimation. Simulation results of ASV roll motion control show better stabilizing performance and minimized energy consumption improved by self-adaptive GPC.
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Kheiralla, A. F., A. Yahya, M. Zohadie, and W. Ishak. "Empirical Models for Power and Energy Requirements II : A Powered Implement Operation in Serdang Sandy Clay Loam, Malaysia." ASEAN Journal on Science and Technology for Development 20, no. 3&4 (December 27, 2017): 349–60. http://dx.doi.org/10.29037/ajstd.359.
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Power and energy requirements were measured with an instrumented tractor for rotary tilling in Serdang sandy clay loam soil. The effects of travel speed and rotor speed upon the measured data were investigated. Power model from orthogonal regression analysis was formulated based on linear and quadratic functions of travel speed and bite length. Fuel consumption model from regression analysis was formulated based on linear tractor PTO power as well as linear equivalent tractor PTO power. Fuel consumption rates predicted by ASAE D497.3 were found to be 25% to 28% overestimates of the values predicted by the model developed. However, fuel consumption rates reported by OECD Tractor Test were found to be 1% to 9% lower than the fuel consumption rates predicted by the model developed. A comparison of power and energy requirements for both powered and draught implements showed that the disk harrow was the most energy efficient implement in terms of fuel consumption and specific energy followed by the rotary tiller, disk plough and mouldboard. Finally, average PTO power, fuel consumption, wheel slip, wheel power and specific energy for a powered implement are presented.
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Gonzalez Morales, Carolina, Miller Alonso Camargo-Valero, Francisco José Molina Pérez, and Belén Fernández. "Effect of the stirring speed on the struvite formation using the centrate from a WWTP." Revista Facultad de Ingeniería Universidad de Antioquia, no. 92 (May 21, 2019): 42–50. http://dx.doi.org/10.17533/10.17533/udea.redin.20190518.
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The formation of struvite (MgNH4PO4·6H2O) for nutrient recovery in wastewater treatment plants has been widely investigated; however, little attention has been paid to the effect of stirring speeds on the resulting particle size, which could affect its agronomic value as a slow-release fertilizer. In this study, struvite formation from the centrate of sewage digestate was performed under six stirring speeds (0, 100, 200, 300, 400, 500 rpm). The resulting struvite crystals were characterised using X-ray diffraction and scanning electron microscopy with energy dispersive X-ray spectroscopy. The average particle size of struvite crystals increased from 55 µm at 0 rpm to 127 µm at 100 rpm and 128 μm at 200 rpm. Further increments in stirring speeds resulted in smaller crystal sizes. These results indicated that the largest particle size can be obtained at stirring speeds ranging from 100 to 200 rpm, equivalent to a velocity gradient between 79 and 188 s-1, as there was no statistically significant difference between mean values (t-test, p<0.05). The optimum stirring speed range reported herein can be used to set operational conditions for struvite crystallisation with the benefit of producing large crystals and reducing energy consumption in stirring tanks.
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Tang, Chang Liang, Dong Jiang Han, Jin Fu Yang, and Xing Jian Dai. "Damper Optimization Design of High-Speed Energy Storage Flywheel Shafting with a Single Point Flexible Support." Applied Mechanics and Materials 672-674 (October 2014): 509–17. http://dx.doi.org/10.4028/www.scientific.net/amm.672-674.509.
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The flywheel energy storage technology is a new type of conversion and storage for electric energy, and it is also a research hotspot of energy field in the world. There are a large number of studies on dynamic characteristics of energy storage flywheel in recent years. The flexible support with a single point has small load-carrying ability but very low friction loss, which is appropriate to be used in small flywheel system. By using a small stiffness pivot-jewel bearing and an oil damper as the lower support of the flywheel, a high-speed flywheel shafting with a single point flexible support was built. The dynamic model of the shafting was obtained by means of the Lagrangian equation. Based on the same energy dissipation of oil damper and flywheel, the optimal equivalent damping of flywheel was determined. The optimization criteria for dynamic state and parameters between oil damper and shafting were also presented. The lower damper’s effects on the mode shapes, modal damping ratios and forced vibration were discussed.
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Guo, Lu, Renwei Mao, Zhifang Liu, Shiqiang Li, Guiying Wu, and Zhihua Wang. "Dynamic Large Deflection Response of RC Beams under Low-Speed Impact Loading." Shock and Vibration 2020 (October 21, 2020): 1–15. http://dx.doi.org/10.1155/2020/8812890.
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The dynamic large deflection response of RC beams under low-speed impact loading at their midspan is investigated in this paper. Two simple methods such as extended Hamilton’s principle and equivalent static hypothesis are used to establish the theoretical models for both simply supported and fully clamped RC beams; analytical formulas for the maximum midspan deflection-input impact energy are obtained. The “equal area” method based on the deflection history of beams is only used during these derivations to determine the plastic bending moment and the stress distribution of the structure. Then, finite element simulations are carried out to verify the validity of the proposed predictions. It is shown that the maximum deflections for both simply supported and fully clamped beams are almost proportional with respect to the input impact energy, which agrees well with both simulations and other experimental results. Also, the boundary condition has more effect on the deflection response of the RC beams which is relatively longer.
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Baudinette, R. V., G. K. Snyder, and P. B. Frappell. "Energetic cost of locomotion in the tammar wallaby." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 262, no. 5 (May 1, 1992): R771—R778. http://dx.doi.org/10.1152/ajpregu.1992.262.5.r771.
Full textAbstract:
Rates of oxygen consumption and blood lactate levels were measured in tammar wallabies (Macropus eugenii) trained to hop on a treadmill. In addition, the work required to overcome wind resistance during forward locomotion was measured in a wind tunnel. Up to approximately 2.0 m/s, rates of oxygen consumption increased linearly with speed and were not significantly different from rates of oxygen consumption for a quadruped of similar body mass. Between 2.0 and 9.4 m/s, rates of oxygen consumption were independent of hopping speed, and between 3.9 and 7.9 m/s, the range over which samples were obtained, blood lactate levels were low (0.83 +/- 0.13 mmol.min-1.kg-1) and did not increase with hopping speed. The work necessary to overcome drag increased exponentially with speed but increased the energy cost of locomotion by only 10% at the average speed attained by our fast hoppers. Thus, during hopping, the energy cost of locomotion is effectively independent of speed. At rates of travel observed in the field, the estimated energy cost of transport in large macropods is less than one-third the cost for a quadruped of equivalent body mass. The energetic savings associated with this unique form of locomotion may have been an important physiological adaptation, enabling large macropods to efficiently cover the distances necessary to forage in the semiarid landscapes of Australia.
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Fu, Meng, Jianghong Li, Aiqi Zhao, Yafeng Wu, Zuhao Chen, and Haowei Zhang. "Nonlinear Self-Excited Vibration Mechanism for Under-Actuated Oil-Well Drilling System with Stick-Slip Vibration." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 37, no. 4 (August 2019): 802–8. http://dx.doi.org/10.1051/jnwpu/20193740802.
Full textAbstract:
Exploration of oil or gas wells is usually carried out by using drilling system. When the kilometers of drilling system is externally disturbed, the drilling system is prone to undesired stick-slip vibration of the drill-string. The stick-slip vibration of the drill-string belongs to the nonlinear self-excited vibration. In order to study the vibration mechanism, the model for the nonlinear torque on the bit by using Karnopp friction model and the two degrees of freedom model for drilling system were established. The equivalent damping torque formula and the energy variation formula of the drilling system were proposed. The mechanism of the nonlinear self-excited vibration of the drilling system was explained. The simulation results indicated that the stick-slip vibration of the drill-string was caused by the negative value of the equivalent damping force of the drilling system. The equivalent damping torque made the positive work on the system, so that the system absorbed the vibration energy from the outside, which destroyed the stability of the system equilibrium point. The feedback effect in the speed of the drill-bit regulates the system energy to maintain constant vibration without attenuation. In each vibration cycle, the energy input by the system is equal to the energy dissipated by the system. The energy absorbed by the drilling system is mainly converted into the potential energy.